RODI Unit efficiency

[psumms]

Does anyone have actual evidenced backed input on the most efficient way to run a five-stage RODI unit?

Is it better to run in small, frequent batches (example: 1 hour per day, 7 days per week), or occasional longer sessions (example: 7 hours once per week)?

I'm thinking mainly from a DI longevity point of view, I get pretty good mileage from my other stages - I run for a max 3 hours per day and produce around 120 gallons/week and my DI lasts approx. 4 weeks (I change when the TDS meter reports 1) using my Glamorca RODU unit, all automated with flush etc. using my Apex and Neptune solenoid valves.

 

[KStatefan]

If you are eliminating any TDS creep when starting the system it does not mater with the respect of DI longevity.

 

[EeyoreIsMySpiritAnimal]

If you are eliminating any TDS creep when starting the system it does not mater with the respect of DI longevity.

How does one do this? (eliminate tds creep?)

 

[KStatefan]

How does one do this? (eliminate tds creep?)

On my system at home I use a DI bypass that sends the first few minutes of permeate down the drain instead of the DI resin. The system at work flushes the membrane with RODI water when it shuts down so there is no TDS to creep to the permeate side of the membrane.

 

[Dbichler]

With a flush valve after ro membranes I turn mine on before making water for a couple minutes and after for a couple minutes

 

[Gadbery]

My 6 stage is taking 8-9 hours to make 30 gallons….. really confused on my. I got it used. May buy and replace all filters to see if that fixes this issue a bit

 

[OldRed1]

My 6 stage is taking 8-9 hours to make 30 gallons….. really confused on my. I got it used. May buy and replace all filters to see if that fixes this issue a bit

What’s your psi going into the system?

 

[KStatefan]

My 6 stage is taking 8-9 hours to make 30 gallons….. really confused on my. I got it used. May buy and replace all filters to see if that fixes this issue a bit

Depending on what membrane that could be correct 80-90 gpd

 

[Gadbery]

What’s your psi going into the system?

Gauge reads 40psi. That’s hooked up straight to my houses hose standoff

 

[Gadbery]

Depending on what membrane that could be correct 80-90 gpd

No idea what membrane it has. Got it used. Is there a way to tell what flow rate membrane it has?

 

[Joj]

As a guesstimate, you can try looking at the flow restrictor for a number printed on it (ie 550). Usually the flow restictor will correlate with what size membrane it has as they are usually paired together from the factory.

 

[Opus]

Gauge reads 40psi. That’s hooked up straight to my houses hose standoff

If true, that is about as low as you can go and still be useful. You want it somewhere around 70 to 80psi. Some will run it over 100psi for better production. You should find your home's water valve and see if it has a pressure valve that can be changed. Many homes have one. If not, then you should consider getting a booster pump.

 

[lefkonj]

I have a whole house water filter so the filters and stuff last a really long time. I run my RODI unit for about 10 hours once every 2 weeks.

 

[KStatefan]

No idea what membrane it has. Got it used. Is there a way to tell what flow rate membrane it has?

There might be a label on the membrane I know there are on Filmtec and Spectrapure membranes. I averaged 75 gpd with a filmtec TW30-1812-50HR @ 64°F & 78 psi. With a Spectrapure Select Plus I am averaging 90 gpd & 72°F & 77 psi.

As @Opus said getting your pressure up will increase production and salt rejection.

 

[OldRed1]

I run my BRS RODI unit at 85psi. You should check the manufacturers guide of your unit to learn what psi it needs to be run at. You may ultimately need to buy a booster pump for your unit.

 

[Gadbery]

If true, that is about as low as you can go and still be useful. You want it somewhere around 70 to 80psi. Some will run it over 100psi for better production. You should find your home's water valve and see if it has a pressure valve that can be changed. Many homes have one. If not, then you should consider getting a booster pump.

I think my pressure gauge is inline after the first 3-4 stages. I’ll have to look at it more closely to see what is set up in what order. I do have a little white oblong thing that says 550 on it but it’s online after the membrane going to the waste line I think. I’ll have to look at it when I get home and make sure everything is connected in the right order

 

[Opus]

I think my pressure gauge is inline after the first 3-4 stages. I’ll have to look at it more closely to see what is set up in what order. I do have a little white oblong thing that says 550 on it but it’s online after the membrane going to the waste line I think. I’ll have to look at it when I get home and make sure everything is connected in the right order

The 550 is in the correct spot. You want it on the wasteline so it puts pressure on the water to force it thru the RO membrane. 550 means you have a 75-90/gal membrane if it is sized correctly.
The pressure gauge should be before the RO membrane. If you put it before any of the filters then it will tell you your water pressure from the faucet. If you put it after the pre-filters but before the RO membrane then it will tell you the pressure your membrane is working with. It is a good idea to get a base line reading if doing it this way using brand new pre-filters because as they do their job they will become clogged and the pressure will drop. This is one of the ways to determine it is time to change them.

 

[Gadbery]

The 550 is in the correct spot. You want it on the wasteline so it puts pressure on the water to force it thru the RO membrane. 550 means you have a 75-90/gal membrane if it is sized correctly.
The pressure gauge should be before the RO membrane. If you put it before any of the filters then it will tell you your water pressure from the faucet. If you put it after the pre-filters but before the RO membrane then it will tell you the pressure your membrane is working with. It is a good idea to get a base line reading if doing it this way using brand new pre-filters because as they do their job they will become clogged and the pressure will drop. This is one of the ways to determine it is time to change them.

Thanks. I haven’t changed the filters as I was told they should be good. I’ll probably order a filter replacement set and start there. As that’s probably the issue